Sensitivity of patient-specific vertebral finite element model from low dose imaging to material properties and loading conditions.

Patient-specific modeling could help in predicting vertebral osteoporotic fracture. The accuracy requirement for input data available in clinical routine is related to the model sensitivity. The objective of this study is to assess the relative impact of material properties and of loading conditions on vertebral strength using a finite element model. Fourteen subject-specific vertebral finite element models were used to investigate the effect of material properties and loading conditions. A design of experiment was set to study three parameters: Young's moduli of trabecular bone and cortico-trabecular bone (outer 3 mm of the vertebra), and load location. Cortico-trabecular bone modulus variation from 270 to 478 MPa made fracture load vary from 22 to 51%, depending on other parameters. Trabecular bone modulus variation from 115 to 258 MPa made fracture load vary from 11 to 43%. Displacing load location by 1 cm resulted in a mean decrease of 48-60% of the fracture load. Anterior bending induced strain concentration in vertebral anterior wall. Material properties of both type of bone have about the same effect. Load location is the most sensitive. Effort should be made to take into account patients' specific load distribution regarding its sagittal balance, in addition to bone properties.